Note 8 - Stockholders' Equity - Warrants (Details) - $ / shares |
6 Months Ended | |
---|---|---|
Jun. 30, 2019 |
Jun. 30, 2018 |
|
Outstanding, number of shares (in shares) | 1,592,775 | |
Outstanding, weighted average exercise price (in dollars per share) | $ 2.55 | |
Outstanding, weighted average remaining life (Year) | 2 years 219 days | 175 days |
Issued, number of shares (in shares) | 1,749,171 | |
Issued, weighted average exercise price (in dollars per share) | $ 0.50 | |
Issued, weighted average remaining life (Year) | 4 years 219 days | |
Exercised, number of shares (in shares) | ||
Exercised, weighted average exercise price (in dollars per share) | ||
Expired or cancelled, number of shares (in shares) | ||
Expired or cancelled, weighted average exercise price (in dollars per share) | ||
Outstanding , number of shares (in shares) | 3,341,946 | |
Outstanding , weighted average exercise price (in dollars per share) | $ 1.48 |